PROJECT SUMMARY: This training grant, currently in its 40th year of funding, represents the primary support for graduate students in the Immunology Training Program at the University of Chicago. The program functions in a diverse environment where the basic biological sciences and the medical school are integrated within the same division in a single campus in Hyde Park, Chicago, IL. It is embodied by the Committee on Immunology, an interdisciplinary and interdepartmental academic unit that serves as the scientific community for immunology graduate students, postdocs, and faculty at the University. The faculty of our Training Program is composed of 34 distinguished trainers selected for their outstanding research and training records, their well- funded laboratories and their dynamic involvement in all aspects of the program. They form a diverse, age- and gender-balanced group whose research spans a broad spectrum of modern areas of immunology including cellular and molecular immunology, biochemistry, genomics, systems biology, microbiome studies, molecular engineering, and human immunology, with a proven record of interdisciplinary collaborations. New strength is drawn from the recent recruitment of five internationally recognized senior faculty with expertise in immunoengineering and immunogenetics, as well as three junior faculty with expertise in systems immunology, mucosal immunology, and myeloid disorders. Predoctoral students receive advanced training through courses focused on the critical analysis of primary literature and experimental design, with special emphasis on computational skills, rigor and reproducibility, and the responsible conduct of research. The comprehensive training includes a weekly Seminar Series, Work-in-Progress forum, and Journal Club, as well as an annual Joint Immunology Retreat held with other top immunology programs in the Midwest. Career development is enhanced through MyChoice, an institutional program enabling trainees to further develop academic skills and gain exposure to a broad array of research-intensive career paths, as well as a partnership with the UChicago Polsky Center for Entrepreneurship and Innovation. The Biological Sciences Division provides strong institutional support, as shown by sustained financial and administrative support, the operation of cutting-edge core facilities such as gnotobiotics, and the implementation of major initiatives such as the Duchossois Family Institute, a new research institute aimed at harnessing the power of the microbiome and immunity for human health. The Program is continuously and rigorously evaluated with respect to organization, leadership, objectives and outcomes. This is one of the most outstanding and competitive training programs in the country, as shown by the high retention and completion rates of our trainees (which include many students from underrepresented minority backgrounds), their impressive publication rate (average of six publications per trainee, including many first-author publications in journals such as Nature, Immunity, Cell Host & Microbe, JEM, and PNAS), and their success in securing independent scientific careers.